The present invention generally relates to Micro-Electro-Mechanical Systems (MEMS), and more particularly, relates to a MEMS microstructure having a shielded conductive path.
Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronic elements onto a common substrate through the utilization of micro-fabrication technology. As a result, smarter products can be developed because a MEMS apparatus makes possible the realization of a complete electro-mechanical system on a substrate. The resulting elector-mechanical systems are smaller, lighter, more functional, less expensive to manufacture, and more reliable than conventional elector-mechanical systems. Because of these benefits, MEMS are being employed in applications that require the MEMS to sense and control the local environment. The sensor elements of the MEMS are able to gather information from the environment through the measure of thermal, biological, chemical, optical, and magnetic phenomena. While the control elements of the MEMS apparatus are able to process the gathered information to control the local environment for a desired outcome or purpose.
One such environment requires the MEMS apparatus to be in contact with a conductive fluid, such as conductive ink. As a result, the conductive paths of the MEMS apparatus are prone to electrical shorting. The conventional technique to prevent electrical shorting of the conductive paths in contact with conductive fluids is to encapsulate the conductive paths with a dielectric material such as polyimide. Although polyimide offers adequate insulation properties, it is often desirable to add an additional layer of protection between the conductive fluid and the conductive paths of the MEMS apparatus. For example, polyimide is used in the art of inkjet printhead technology to form an ink holding cavity and to insulate the conductive paths leading to an inkjet ejector. However, the conductive paths leading to an inkjet ejector lie directly below the ink holding cavity formed by the polyimide. Consequently, the polyimide that forms the ink holding cavity also acts as the insulator that prevents an electrical short between the conductive path and the conductive fluid. Hence, a single point breakdown in the polyimide results in failure of the inkjet printhead.
Moreover, a layer of insulating material such as polyimide provides no protection from Electromagnetic Interference (EMI). As a result, the MEMS are susceptible to EMI and may produce an undesired or unwanted response, cease to function, or exhibit a degradation of performance. Because a sudden change in voltage or current in a transmitted signal may cause EMI, neighboring conductive paths are especially susceptible.
Consequently, the conductive paths of a MEMS apparatus are susceptible to EMI from neighboring conductive paths and from other EMI sources operating in the proximity of the apparatus. The effects of EMI are more pronounced where the MEMS application requires the use of a high frequency modulated waveform. Since MEMS devices typically have high resonant frequencies, high frequency waveforms are a necessity to control and monitor the devices.
As a result, the layout of conductive paths in a MEMS apparatus becomes critical. But due to the miniaturized nature of a MEMS apparatus, the layout of conductive paths to avoid the effects of EMI from adjacent conductive paths and/or to avoid contact with conductive fluids in the envisioned operating environment is not always possible and exceedingly difficult. As a result, the growth of MEMS apparatuses in certain environments, for example, inkjet printheads, has been slowed.
The present invention addresses the above described limitations of conventional conductive paths in MEMS apparatuses. The present invention provides an approach to minimize the potential for electrical shorts in a MEMS apparatus that may contact a conductive fluid and provides an approach overcome a MEMS susceptibility to Electromagnetic Interference.
According to one aspect of the present invention, a method is practiced to form an electrical connection in a MEMS apparatus. Layers of conductive material and non-conductive material are interleaved to form an electrical connection having a center conductor and a shield.
According to another aspect of the present invention, a method is practiced to form an electrical connection in a MEMS apparatus. Layers of conductive material and non-conductive material are interleaved to form an electrical connection having a center conductor, a first shield and a second shield.
The present invention also provides a MEMS structure for shielding a conductive pathway in the MEMS apparatus, wherein the structure may include a first shield and a second shield for shielding the conductive pathway from adverse environmental phenomena in which a MEMS apparatus operates.